Surface treatment of titanium or titanium base alloy



United States Patent 3,085,949 SURFACE TREATMENT OF TITANIUM 0R TITANIUMBASE ALLDY Harry Rowland Leech and Frank Riding, Widues, England,assignors to Imperial Chemical Industries Limited, London, England, acorporation of Great Britain No Drawing. Filed Mar. 31, 19%, Ser. No.18,884 Claims priority, applicatien Great Britain Apr. 17, 1959 5Claims. (Cl. Zed-29) The present invention relates to improvements in orrelating to the surface treatment of titanium or titanium base alloyarticles for the purpose of preparing a suitably conditioned surface.thereon prior to, for example, electroplating.

In British patent specification No. 758,013 there is detscribed andclaimed inter alia a method of surface treatment of titanium or titaniumbase alloy articles which comprises treatment of the surface of the saidarticles with concentrated hydrochloric acid solution at elevatedtemperatures followed by electrodeposition of a coating of metalthereon.

Said temperature may be 90-100 C. and the article may be pretreated witha standard pickling and de-scaling bath before treatment with thehydrochloric acid.

It has now been found that by treating the surfaces of titanium ortitanium base alloy articles with hydrogen at elevated temperaturessurfaces are formed which have a substantially similar etched appearanceto that produced according to the method described and claimed inBritish patent specification No. 758,013, that is to say surfaces whichare porous, grey and matt in appearance. It has also been found that thesurfaces thus formed likewise permit deposition thereon of asatisfactorily adherent coating of metal.

According to the present invention the method of surface treatment oftitanium or titanium base alloy articles comprises treatment of thesurface of the said articles with hydrogen at elevated temperatures,preferably at a temperature between 600 and 1000 0., followed bydeposition of a coating of a metal thereon, for example platinum,rhodium or iridium or an alloy of two or more of these metals.

It is sometimes desirable to pretreat the articles with a pickling orde-scaling bath before treating them with hydrogen.

By way of example, by passing hydrogen over 16 pieces of titanium 1 /2in. X in. X 16 S.W.G. (0.064 in.) at a temperature between 600 and 1000C. for various periods of time a series of 16 surface treated titaniumspecimens "ice is prepared containing hydrogen over a range of 995 mg.and it is found that a satisfactory adherent electrodeposit of platinumcan be. formed on each piece thus treated. A suitable plating procedurecomprises plating at a current density of about 0.8 amp./ sq. dm. froman aqueous solution of sodium hexahydroxy platinate containing 0.5 to 1%sodium hydroxide. A complete disclosure of suitable plating proceduresand baths may be found in Metal Industry, vol. (November 19', 1954),pages 427-429.

The process of the present invention permits surfaces of titanium ortitanium base alloy articles to be conditioned quickly, without loss oftitanium, and uniformly even in the presence of stresses and welds.

What we claim is:

l. A method of surface treatment of an article selected from the groupconsisting of titanium and titanium base alloy articles which comprisestreating the surface of the said articles with hydrogen at elevatedtemperatures and then depositing a coating of a metal thereon.

2. A method as claimed in claim 1 wherein the elevated temperature isbetween 600 and 1000 C.

3. A method as claimed in claim 1 wherein the article is pretreated witha pickling bath before treating it with hydrogen.

4. A method as claimed in claim 1 wherein the aforesaid metal is a metalselected from the group consisting of platinum, rhodium and iridium andalloys of at least two of these metals.

5. A method as claimed in claim 1 wherein the article is pretreated witha de-scaling bath before treating it with hydrogen.

References Cited in the file of this patent UNITED STATES PATENTS2,714,566 Barton et a1. Aug. 2, 1955 2,719,797 Rosenblatt Oct. 4, 19552,772,227 Quaely et al Nov. 27, 1956 2,835,630 Huddle et al May 20, 19582,841,477 Hall July 1, 1958 2,885,826 Grieve et a1 May 12, 19592,929,766 Withers et al. Mar. 22, 1960 FOREIGN PATENTS 758,013 GreatBritain Sept. 26, 1956 OTHER REFERENCES Abkowitz et al.: Titanium inIndustry, Van Nostrand Co., New York, 1955, pages 3133.

1. A METHOD OF SURFACE TREATMENT OF AN ARTICLE SELECTED FROM THE GROUPCONSISTING OF TITANIUM AND TITANIUM BASE ALLOY ARTICLES WHICH COMPRISESTREATING THE SURFACE OF THE SAID ARTICLES WITH HYDROGEN AT ELEVATEDTEMPERATURES AND THEN DEPOSITING A COATING OF A METAL THEREON.